<html>
  <head>
    <title>Popup window</title>
    <style>
    </style>
  </head>
  <body>
    <div>
      <label>JPEG</label>
      <img id="jpg"/ src="">
    </div>
    <div>
      <label>PNG</label>
      <img id="png" src=""></img>

      <script type="text/javascript">
        var gui = require('nw.gui');
        var win = gui.Window.get();
        win.maximize();
      </script>
    </div>
  </body>
</html>